has_ticket = int(input("请确认是否有票(0/非0)："))     #0没票
if has_ticket:
    knife_length = int(input("请输入刀的长度："))
    if knife_length >=20:
        print("不允许上车")
    else:
        print("安检通过，允许上车")
else:
    print("不允许进门")